scholarly journals The Influence of Fuel and Steam Consumption on Characteristics of Fixed Bed Process of Woody Biomass Steam Gasification with Intensive Heat Supply

2021 ◽  
pp. 13-22
Author(s):  
I. Donskoy
Keyword(s):  
Plant Biomass ◽  
Renewable Energy Sources ◽  
Fixed Bed ◽  
Steam Gasification ◽  
Energy Utilization ◽  
Solar Thermal Energy ◽  
Gasification Process ◽  
Calculation Results ◽  
Calculated Fraction

Plant biomass is one of the most widespread renewable energy sources. Energy utilization of biomass allows solving some problems associated with the development of off-grid energy systems and the processing of combustible waste (primarily agricultural and forestry waste). This paper is devoted to the study of an allothermal gasification process of plant biomass materials using a kinetic-thermodynamic model developed by the author. The gasification process is considered stationary, and steam is used as a gasification agent. The power of the supplied heat is considered constant (10 kW). One of the significant tasks related to allothermal gasification is to choose flowrate parameters so that the heat supplied is efficiently used in chemical reactions without the threat of reactor overheating. The determination of the boundaries of the safe gasifier operation involved variant calculations with a view to optimizing the gasification conditions. The calculation results show that the allothermal gasification process can proceed with a thermochemical efficiency of about 70%. For each fixed fuel consumption level, there is an optimal fuel-steam ratio. The complete conversion of biomass requires sufficiently high temperatures. The produced gas contains a significant steam fraction (>50 vol%) even under optimal conditions. The calculated fraction of hydrogen in dry gas is up to 60vol%. The data obtained can be used to assess the efficiency of energy units with biomass gasification using high-temperature sources, for example, in systems that use and store solar thermal energy.

scholarly journals CFD researched on rice husk gasification in a pilot fixed bed up-draft system

2016 ◽  
Vol 19 (3) ◽  
pp. 96-109
Author(s):  
Phung Thi Kim Le ◽  
Viet Tan Tran ◽  
Thien Luu Minh Nguyen ◽  
Viet Vuong Pham ◽  
Truc Thanh Nguyen ◽  
...  
Keyword(s):  
Mathematical Modeling ◽  
Rice Husk ◽  
Alternative Energy ◽  
Fossil Fuels ◽  
Fixed Bed ◽  
Steam Gasification ◽  
Actual Process ◽  
Ansys Fluent ◽  
Alternative Energy Sources ◽  
Gasification Process

Finding alternative energy sources for fossil fuels was a global matter of concern, especially in developing countries. Rice husk, an abundant biomass in Viet Nam, was used to partially replace fossil fuels by gasification process. The study was conducted on the pilot plant fixed bed up-draft gasifier with two kind of gasification agents, pure air and air-steam mixture. Mathematical modeling and computer simulations were also used to describe and optimize the gasification processes. Mathematical modeling was based on Computational Fluid Dynamics method and simulation was carried by using Ansys Fluent software. Changes in outlet composition of syngas components (CO, CO2, CH4, H2O, H2) and temperature of process, in relation with ratio of steam in gasification agents, were presented. Obtained results indicated concentration of CH4, H2 in outlet was increased significantly when using air-steam gasification agents than pure air. The discrepancies among the gasification agents were determined to improve the actual process.

scholarly journals Examination of steam gasification of coal with physically mixed catalysts

2019 ◽  
Vol 21 (4) ◽  
pp. 51-57 ◽  
Author(s):  
Katarzyna Śpiewak ◽  
Grzegorz Czerski ◽  
Agnieszka Sopata
Keyword(s):  
Coal Gasification ◽  
Steam Gasification ◽  
Conversion Degree ◽  
Process Time ◽  
Gasification Process ◽  
Kinetics Of Formation ◽  
Short Time ◽  
Kinetics Of ◽  
Positive Effect

Abstract The aim of this study was to analyse the steam gasification process of ‘Janina’ coal with and without Na-, K- and Ca-catalysts. The catalysts were physically mixed with the coal due to the simplicity of this method, short time of execution and certainty that the amount of catalyst is exactly as the adopted one. The isothermal measurements were performed at 800, 900 and 950°C and a pressure of 1 MPa using thermovolumetric method. The obtained results enabled assessment of the effect of analysed catalysts on the process at various temperatures by determination of: i) carbon conversion degree; ii) yield and composition of the resulting gas; and iii) kinetics of formation reactions of main gas components – CO and H2. The addition of catalysts, as well as an increase in operating temperature, had a positive effect on the coal gasification process – reactions rates increased, and the process time was reduced.

Air-Steam Gasification of Dairy Biomass Using Small Scale Fixed Bed Gasifier

2009 ◽  
Author(s):  
Gerardo Gordillo ◽  
Kalyan Annamalai
Keyword(s):  
Energy Conversion ◽  
Fixed Bed ◽  
Energy Conversion Efficiency ◽  
Steam Gasification ◽  
Small Scale ◽  
Gasification Process ◽  
Green Power ◽  
Endothermic Process ◽  
Conversion Efficiencies ◽  
Rich Mixtures

The composition of gases obtained from gasification of biomass fuels depends principally upon parameters like fuel and oxidizing medium supplied, equivalence ratio (Φ), steam-fuel ratio (S:F), pressure, reaction temperature, and residence time in the gasifier. Gasification with steam only is an endothermic process which produces rich mixtures of CO and H2 while gasification with air-steam may not require heat input in order to produce H2 rich mixtures of CO and CO2. Furthermore, gases produced by gasification with-air-steam can be supplied to a shift reactor to produce mixtures of H2, CO2, and N2. When pure O2 is used instead of air, the H2 separated from CO2 can be used for in situ sustainable green power generation. The gasification process can handle low quality fuel and larger sized particles. While coal has higher fixed carbon (FC) providing more heat for gasification, the Dairy biomass (DB) selected in current study has lower FC and hence contributes less heat. While most of the past studies deal with gasification of coal, current study concentrates on DB as fuel. Experimental results are presented for gasification of i) dairy biomass (DB) and ii) DB ash blends (DBAB) using a 10 KW fixed bed counter-flow gasifier and air-steam as oxidizing source. The results show that the reactor operates almost adiabatically. The effects of the Φ and S:F ratio on peak temperatures, gas composition, gross heating value of the products (HHV), and energy conversion efficiency (ECE) are investigated. A mass spectrometer has been used to analyze the composition of gases in real time continuously. Increasing Φ or S:F increases the production of H2 and CO2 but decreases the production of CO; thus, the reaction of CO+H2O→CO2+H2 seems to control the composition of gases. The operating parameters include 1.59<Φ<6.36 and 0.36<S:F<0.8. Energy Conversion efficiencies (ECE) range from 0.26 to 0.80.

scholarly journals Torrefaction as a Valorization Method Used Prior to the Gasification of Sewage Sludge

Energies ◽  
2019 ◽  
Vol 12 (1) ◽  
pp. 175 ◽  
Author(s):  
Halina Pawlak-Kruczek ◽  
Mateusz Wnukowski ◽  
Lukasz Niedzwiecki ◽  
Michał Czerep ◽  
Mateusz Kowal ◽  
...  
Keyword(s):  
Sewage Sludge ◽  
Fossil Fuels ◽  
Fixed Bed ◽  
Electricity Consumption ◽  
Pilot Scale ◽  
Positive Influence ◽  
Steam Gasification ◽  
Gasification Process ◽  
Pilot Scale Reactor ◽  
Scale Reactor

The gasification and torrefaction of sewage sludge have the potential to make the thermal utilization of sewage sludge fully sustainable, thus limiting the use of expensive fossil fuels in the process. This includes sustainability in terms of electricity consumption. Although a great deal of work has been performed so far regarding the gasification of sewage sludge and some investigations have been performed in the area of its torrefaction, there is still a gap in terms of the influence of the torrefaction of the sewage sludge on its subsequent gasification. This study presents the results from the torrefaction tests, performed on a pilot scale reactor, as well as two consecutive steam gasification tests, performed in an allothermal fixed bed gasifier, in order to determine if torrefaction can be deemed as a primary method of the reduction of tar content for the producer gas, from the aforementioned gasification process. A comparative analysis is performed based on the results obtained during both tests, with special emphasis on the concentrations of condensable compounds (tars). The obtained results show that the torrefaction of sewage sludge, performed prior to gasification, can indeed have a positive influence on the gas quality. This is beneficial especially in terms of the content of heavy tars with melting points above 40 °C.

scholarly journals THE ANALYSIS OF THE USAGE AND PERSPECTIVES OF RENEWABLE ENERGY SOURCES IN LITHUANIA / ATSINAUJINANČIŲ ŠALTINIŲ PANAUDOJIMO IR PERSPEKTYVŲ LIETUVOJE ANALIZĖ

2011 ◽  
Vol 3 (1) ◽  
pp. 73-77
Author(s):  
Dominykas Vasarevičius
Keyword(s):  
Renewable Energy ◽  
Solar Energy ◽  
Renewable Energy Sources ◽  
Climatic Conditions ◽  
Energy Utilization ◽  
Energy Sources ◽  
Solar Thermal Energy ◽  
Policy Model ◽  
Advantages And Disadvantages ◽  
Private Households

The paper presents the current situation with the renewable energy sources in Lithuania. An overview of legislation promoting the production and usage of renewable energy in Lithuania is presented. Renewable energy production methods suitable for Lithuanian conditions, their advantages and disadvantages are discussed. It is shown that there is no any promotion from the state for usage of solar energy in private households. The potential of solar energy usage is determined. In order to show the effectiveness of solar thermal energy utilization under similar climatic conditions presented the example of promotion policy model and its results in Poland.

scholarly journals Experimental Study and Thermodynamic Analysis of Hydrogen Production through a Two-Step Chemical Regenerative Coal Gasification

2019 ◽  
Vol 9 (15) ◽  
pp. 3035 ◽  
Author(s):  
Li ◽  
He ◽  
Li
Keyword(s):  
Hydrogen Production ◽  
Production Process ◽  
Coal Gasification ◽  
Fixed Bed ◽  
H2 Production ◽  
Steam Gasification ◽  
Air Separation ◽  
The Novel ◽  
Separation Unit ◽  
Gasification Process

Hydrogen, as a strategy clean fuel, is receiving more and more attention recently in China, in addition to the policy emphasis on H2. In this work, we conceive of a hydrogen production process based on a chemical regenerative coal gasification. Instead of using a lumped coal gasification as is traditional in the H2 production process, herein we used a two-step gasification process that included coking and char-steam gasification. The sensible heat of syngas accounted for 15–20% of the total energy of coal and was recovered and converted into chemical energy of syngas through thermochemical reactions. Moreover, the air separation unit was eliminated due to the adoption of steam as oxidant. As a result, the efficiency of coal to H2 was enhanced from 58.9% in traditional plant to 71.6% in the novel process. Further, the energy consumption decreased from 183.8 MJ/kg in the traditional plant to 151.2 MJ/kg in the novel process. The components of syngas, H2, and efficiency of gasification are herein investigated through experiments in fixed bed reactors. Thermodynamic performance is presented for both traditional and novel coal to hydrogen plants.

scholarly journals Mathematical modeling of thermal decomposition of resins in the process of reversed gasification of plant biomass

2020 ◽  
Vol 22 (5) ◽  
pp. 83-93
Author(s):  
I. G. Donskoy
Keyword(s):  
Thermal Decomposition ◽  
Plant Biomass ◽  
Fixed Bed ◽  
Kinetic Scheme ◽  
Gasification Process ◽  
Bed Height ◽  
Oxidation Stage ◽  
Optimal Values ◽  
Gasification Efficiency ◽  
Limiting Values

THE PURPOSE. Of this work is to estimate parameters for a sufficiently comlete thermal decomposition of tarry products of the fixed-bed gasification of wood fuel. METHODS. To this end, mathematical models are used in different statements: the decomposition of the tar is considered in the approximations of one- and two-reaction kinetic scheme; to assess the influence of the bed height and temperature, the convection-diffusionreaction equation with a given temperature distribution along the length of the reaction zone is used; the temperature of the gasification process is estimated from experimental data and thermodynamic calculations. Along with the numerical model of the decomposition of the tar, a simplified analytical expression (for large Peclet numbers) is applied, the limits of its applicability are determined. RESULTS. Of calculations show that the efficiency of the airblown gasification of wood is determined by the temperature level of the oxidation stage: in the range of modes in which the optimal values of efficiency are achieved, the conversion of tarry products does not proceed sufficiently completely due to kinetic limitations; an increase in the specific consumption of the oxidizer leads to a decrease in efficiency due to stoichiometric reasons. CONCLUSION. Physicochemical limitations do not allow reaching the limiting values of gasification efficiency, shifting the optimal modes towards increasing the specific air consumption; a decrease in the yield of tar requires, first of all, changes in the thermal modes of gasification (for example, external heating or an increase in the oxygen concentration).

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